[flutter_tools] add support for dart defines to flutter test (#70791)

dev/automated_tests/flutter_test/dart_defines_expectation.txt

+[0-9]+:[0-9]+ [+]1: All tests passed!

dev/automated_tests/flutter_test/dart_defines_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('Dart defines can be provided', () {
+    expect(const String.fromEnvironment('flutter.test.foo'), 'bar');
+  });
+}

packages/flutter_tools/lib/src/commands/test.dart

@@ -31,6 +31,7 @@ class TestCommand extends FlutterCommand {
     addNullSafetyModeOptions(hide: !verboseHelp);
     usesTrackWidgetCreation(verboseHelp: verboseHelp);
     addEnableExperimentation(hide: !verboseHelp);
+    usesDartDefineOption();
     argParser
       ..addMultiOption('name',
         help: 'A regular expression matching substrings of the names of tests to run.',
@@ -184,6 +185,18 @@ class TestCommand extends FlutterCommand {
     final String excludeTags = stringArg('exclude-tags');
     final BuildInfo buildInfo = await getBuildInfo(forcedBuildMode: BuildMode.debug);
 
+    if (buildInfo.packageConfig['test_api'] == null) {
+      globals.printError(
+        '\n'
+        'Error: cannot run without a dependency on either "package:flutter_test" or "package:test". '
+        'Ensure the following lines are present in your pubspec.yaml:'
+        '\n\n'
+        'dev_dependencies:\n'
+        '  flutter_test:\n'
+        '    sdk: flutter\n',
+      );
+    }
+
     if (buildTestAssets && flutterProject.manifest.assets.isNotEmpty) {
       await _buildTestAsset();
     }

packages/flutter_tools/lib/src/test/runner.dart

@@ -90,9 +90,6 @@ class _FlutterTestRunnerImpl implements FlutterTestRunner {
   }) async {
     // Configure package:test to use the Flutter engine for child processes.
     final String shellPath = globals.artifacts.getArtifactPath(Artifact.flutterTester);
-    if (!globals.processManager.canRun(shellPath)) {
-      throwToolExit('Cannot execute Flutter tester at $shellPath');
-    }
 
     // Compute the command-line arguments for package:test.
     final List<String> testArgs = <String>[

packages/flutter_tools/lib/src/test/test_compiler.dart

@@ -5,7 +5,6 @@
 import 'dart:async';
 
 import 'package:meta/meta.dart';
-import 'package:package_config/package_config.dart';
 
 import '../artifacts.dart';
 import '../base/file_system.dart';
@@ -114,8 +113,6 @@ class TestCompiler {
     return residentCompiler;
   }
 
-  PackageConfig _packageConfig;
-
   // Handle a compilation request.
   Future<void> _onCompilationRequest(_CompilationRequest request) async {
     final bool isEmpty = compilationQueue.isEmpty;
@@ -126,25 +123,6 @@ class TestCompiler {
     if (!isEmpty) {
       return;
     }
-    if (_packageConfig == null) {
-      _packageConfig ??= buildInfo.packageConfig;
-      // Compilation will fail if there is no flutter_test dependency, since
-      // this library is imported by the generated entrypoint script.
-      if (_packageConfig['test_api'] == null) {
-        globals.printError(
-          '\n'
-          'Error: cannot run without a dependency on either "package:flutter_test" or "package:test". '
-          'Ensure the following lines are present in your pubspec.yaml:'
-          '\n\n'
-          'dev_dependencies:\n'
-          '  flutter_test:\n'
-          '    sdk: flutter\n',
-        );
-        request.result.complete(null);
-        await compilerController.close();
-        return;
-      }
-    }
     while (compilationQueue.isNotEmpty) {
       final _CompilationRequest request = compilationQueue.first;
       globals.printTrace('Compiling ${request.mainUri}');
@@ -158,7 +136,7 @@ class TestCompiler {
         request.mainUri,
         <Uri>[request.mainUri],
         outputPath: outputDill.path,
-        packageConfig: _packageConfig,
+        packageConfig: buildInfo.packageConfig,
       );
       final String outputPath = compilerOutput?.outputFilename;
 

packages/flutter_tools/test/general.shard/test_compiler_test.dart

@@ -114,29 +114,6 @@ void main() {
     ProcessManager: () => FakeProcessManager.any(),
     Logger: () => BufferLogger.test(),
   });
-
-  testUsingContext('TestCompiler reports an error when there is no dependency on flutter_test or test', () async {
-    final FakeTestCompiler testCompiler = FakeTestCompiler(
-      BuildInfo.debug,
-      FlutterProject.current(),
-      residentCompiler,
-    );
-
-    expect(await testCompiler.compile(Uri.parse('test/foo.dart')), null);
-    expect(testLogger.errorText, contains('Error: cannot run without a dependency on '
-      'either "package:flutter_test" or "package:test'));
-    verifyNever(residentCompiler.recompile(
-      any,
-      <Uri>[Uri.parse('test/foo.dart')],
-      outputPath: testCompiler.outputDill.path,
-      packageConfig: anyNamed('packageConfig'),
-    ));
-  }, overrides: <Type, Generator>{
-    FileSystem: () => fileSystem,
-    Platform: () => linuxPlatform,
-    ProcessManager: () => FakeProcessManager.any(),
-    Logger: () => BufferLogger.test(),
-  });
 }
 
 /// Override the creation of the Resident Compiler to simplify testing.

packages/flutter_tools/test/integration.shard/test_test.dart

@@ -82,6 +82,11 @@ void main() {
     return _testFile('package_assets', automatedTestsDirectory, flutterTestDirectory, exitCode: isZero);
   });
 
+  testWithoutContext('flutter test should support dart defines', () async {
+    return _testFile('dart_defines', automatedTestsDirectory, flutterTestDirectory, exitCode: isZero,
+      extraArguments: <String>['--dart-define=flutter.test.foo=bar']);
+  });
+
   testWithoutContext('flutter test should run a test when its name matches a regexp', () async {
     final ProcessResult result = await _runFlutterTest('filtering', automatedTestsDirectory, flutterTestDirectory,
       extraArguments: const <String>['--name', 'inc.*de']);